WATER POLLUTION

• Introduction
• Sources of water Pollution
• Classification of water pollutants
• Water Quality Standards
• Effects of water pollution

INTRODUCTION

Contamination

Pollution

Pollutants

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SOURCES OF WATER POLLUTION

Point Source: Any single identifiable source of pollution from which pollutants are discharged

Non point Source: Sources of pollution are scattered or diffuse and can not be readily identified

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POINT SOURCE

• Pollution occurs from a single identifiable source
• Discharge of effluents occurs at one point
• Effect is high
• Easier to manage and control
• Ex. Industries, faulty treatment plant, oil tank spills, sewer outfalls etc.

NON POINT SOURCE

• Pollution occurs through many scattered sources
• Caused by discharge of pollutants over a wide area
• Effect is low
• Very difficult to manage and control
• Ex. Farming pesticides and fertilizers, road salt runoff etc.

CLASSIFICATION OF WATER POLLUTANTS

On the basis of their source

1. Natural Pollutants : The pollutants released in environment due to natural activities like Volcanic eruption, forest fire, storms, decomposition etc.

1. Man-made (anthropogenic) Pollutant : The pollutants produced by different human activities like, Industrialisation, urbanisation, deforestation, mining, use of fertilizers and pesticides etc.

CLASSIFICATION OF WATER POLLUTANTS

On the basis of nature of material

1. Biodegradable : The pollutants which are decomposed naturally

Ex. Sewage, wood, paper, garbage, cardboard etc.

1. Non-biodegradable : The pollutants which can not be decomposed naturally or degrade at very slow rate

Ex. DDT, Plastic, glass, E-waste etc

CLASSIFICATION OF WATER POLLUTANTS

On the basis of their concentration in nature

1. Quantitative pollutants : The pollutants which normally occur in environment but become pollutants if their concentration increases than allowable limit.

Ex. CO₂ in atmosphere

1. Qualitative pollutants : The pollutants which do not occur naturally in environment and added by human activities.

Ex. Pesticides, Insecticides etc.

CLASSIFICATION OF WATER POLLUTANTS

On the basis of form of pollutant

1. Primary pollutants : The substance which remain in same form in environment

- Also, called as direct pollutants

Ex. Smoke, dust, ash, hydrocarbon etc

1. Secondary pollutants : The substance which are formed from primary pollutants.

- Considered more toxic than primary pollutants

Ex. SO₃ , Ketones, Ozone, aldehydes, PAN (Peroxyacyle nitrate) etc.

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WATER QUALITY STANDARDS

• The water quality is physical , chemical and biological properties of water.
• The water quality defines on the basis of its intended use.
• Different type of water use require different level of water purity like, drinking water requires highest standards of purity while irrigation and hydropower generation requires lower quality standards.

WATER QUALITY STANDARDS

1. Physical Parameters:

- The parameters which respond to the sense of sight, taste and smell.

- The user can judge water quality by its physical characteristics

• Chemical Parameters:
• Biological Parameters:

WATER QUALITY STANDARDS

PHYSICAL PARAMETERS

CHEMICAL PARAMETERS

BIOLOGICAL PARAMETERS

-Colour

• Odour and taste
• Suspended solids
• Turbidity
• Temperature

• Total dissolved solids (TDS)
• pH
• Acidity
• Alkalinity
• Hardness
• Chlorides
• Fluorides
• Metals
• Organic matter

Pathogens

• Bacteria
• Viruses
• Protozoa

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WATER QUALITY STANDARDS

1. Indian Standard Institution (ISI)
2. World Health Organization (WHO)
3. Indian Council of Medical Research (ICMR)
4. United States Public Health Services (USPHS)

Physical Parameters

Colour

• Pure water is colorless. Therefore any types of color appearance in water indicates water pollution.
• Natural water system is often colored by foreign material. If color is due to suspended material, it is called as apparent color. Color given by dissolved material that remains even after removal of suspended material is called true color or real color
• Materials decayed from organic matter, namely, vegetation and inorganic matter such as soil, stones, and rocks impart color to water, which is objectionable for esthetic reasons, not for health reason.
• Color is measured by Tintometer. Permissible limit is 15 Hazen units.

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Physical Parameters

Taste & Odour

• Pure water is always tasteless and odorless. Therefore if any types of taste and odor is present, it indicates water pollution.
• Water taste and odor may develops due to natural or artificial regions.
• Artificial region for taste and odor in water is due to (chlorination). Some natural impurities dissolved in water can also give taste and odor.
• Inorganic salts such as NaCl, KCl etc dissolve in water give taste whereas compounds like H₂S can give both taste and odor.
• Compounds giving taste and odor to water may be toxic to consumer, so drinking water should be taste less and odour less.

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Physical Parameters

Suspended Solids

• Total Suspended Solids (TSS) are solids in water that can be trapped by a filter. TSS can include a wide variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage.
• High concentrations of suspended solids can cause many problems for stream health and aquatic life.
• Total suspended solids (TSS) are particles that are larger than 2 microns found in the water column. Anything smaller than 2 microns (average filter size) is considered a dissolved solid.

Physical Parameters

Suspended Solids

• High TSS can block light from reaching submerged vegetation. As the amount of light passing through the water is reduced, photosynthesis slows down. Reduced rates of photosynthesis causes less dissolved oxygen to be released into the water by plants.
• If light is completely blocked from bottom dwelling plants, the plants will stop producing oxygen and will die. As the plants are decomposed, bacteria will use up even more oxygen from the water. Low dissolved oxygen can lead to fish kills.
• High TSS can also cause an increase in surface water temperature, because the suspended particles absorb heat from sunlight. This can cause dissolved oxygen levels to fall even further (because warmer waters can hold less DO), and can harm aquatic life in many other ways, 

Physical Parameters

Turbidity

• Pure water is clear and do not absorb light.
• Turbidity is the cloudiness of water. It is a measure of the ability of light to pass through water.
• It is caused by suspended material such as clay, silt, organic material, plankton, and other particulate materials in water
• Some materials that give turbidity may be toxic to consumers. Therefore turbid water is not suitable for drinking purposes.
• Turbidity prevents penetration of light into deeper layer of natural water system that directly affects photosynthetic organism in bottom.
• Drinking water should have turbidity less than 5 NTU (Naphthalometric turbidity unit)

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Physical Parameters

Turbidity

• Turbidity is measured by an instrument called nephelometric turbidimeter, which expresses turbidity in terms of NTU or TU.
• Turbidity more than 5 NTU can be visible to the average person while turbidity in muddy water, it exceeds 100 NTU.
• Groundwater normally has very low turbidity because of the natural filtration that occurs as the water penetrates through the soil

Physical Parameters

Temperature

• It is one of the important parameter in natural surface water system.
• Desirable limit of temperature for domestic use ranging between 10⁰ C to 20⁰ C.
• The temperature in water governs the kinds and types of aquatic life that live in it.
• It regulates the maximum dissolved oxygen concentration of the water.
• Temperature influences the rate of chemical and biological reactions.
• It affects the dissolved oxygen level in water, photosynthesis of aquatic plants, metabolic rates of aquatic organisms, and the sensitivity of these organisms to pollution, parasites, and disease.

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Chemical Parameters

1. Total Dissolved Solids (TDS)
2. pH
3. Acidity
4. Alkalinity
5. Hardness
6. Chlorides
7. Fluorides
8. Metals
9. Organic matter

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Chemical Parameters

TDS :

• Organic and inorganic particles dissolved in water
• Sizes varies from 10 ^-3 µm to 10 ^-5 µm
• They may impart colour, taste, toxicity and smell in water
• Can be removed by reverse osmosis, electro dialysis, etc.

pH :

• Defined as the negative logarithm of H⁺ ion concentration
• It is measure of degree of acidity or alkalinity of water
• Measured on pH scale, which varies from 0 to 14.
• Potable water should have pH in range of 6.5 to 8.5

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Chemical Parameters

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Acidity :

• Capacity of substance to neutralize OH^- ions
• Due to presence of minerals and dissolution of CO₂
• Causes the corrosion of metals and pipelines

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Alkalinity :

• Capacity of substance to neutralize H⁺ ions (acids)
• Due to presence of bicarbonates, carbonates and hydroxides
• It imparts bitter taste to water

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Chemical Parameters

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Hardness :

• Defined as the soap destroying property of water
• Carbonates and bicarbonates of Calcium and magnesium are responsible of temporary hardness while, sulphates, chlorides and nitrates of calcium and magnesium are responsible for permanent hardness.
• Causes excessive consumption of soap in laundries
• Forms deposits in boiler
• Ground water have more hardness than surface water

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Chemical Parameters

Chlorides :

• Due to intrusion of sea water, industrial wastes and domestic wastes
• Usually present in form of CaCl, NaCl and MgCl
• Imparts salty taste in water

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Fluorides :

• Mainly associated with some sedimentary rocks and igneous rocks
• Harmful and toxic for human and other animals if presented in large quantity while small amount can be beneficial
• Its deficiency can cause dental cavities in children
• Excess amount can cause discoloration of teeth (Fluorosis)

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Chemical Parameters

Metals :

• Added to water by mining, industrial or agricultural sources
• Arsenic, Cadmium, Chromium, lead and mercury are some of the toxic metals
• Excess amount of Sodium cause bitter taste and cause health hazard like cardiac and kidney
• Iron and Manganese impart colour even if presented in small quantity

Organic matter :

• Utilized DO of water bodies for their degradation and decreased DO level which affects the aquatic ecosystem

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Biological Parameters

The combined group of pathogenic and non-pathogenic bacteria is termed as B-coli group.

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Bacteria - Cholera, diarrhea, typhoid, jaundice

Protozoa – Amebic dysentery, giardiasis

Viruses – Hepatitis, meningitis, poliomylitis

WATER POLLUTANTS

• Oxygen demanding waste ( BOD, COD)
• Nutrients ( Eutrophication)
• Sediments ( Decreased photosynthesis, lower DO)
• Toxic chemicals ( Bio accumulation, Biomagnification, BCF)
• Pathogens ( Water borne diseases)
• Radioactive materials ( highly harmful)
• Thermal Pollutants ( Lower DO, increased biological actitivities, death of heat sensitivity organisms)

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EUTROPHICATION

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EUTROPHICATION

1. Oligotrophic:

Water bodies with poor concentration of nutrients and very low productivity of aquatic plants

• Mesotrophic :

Water bodies with moderate concentration of nutrients and average productivity of aquatic plants

• Eutrophic :

Water bodies with very high concentration of nutrients and very high productivity of aquatic plants

Control of Water Pollution

• By proper sewage treatment
• Proper treatment of industrial effluents
• Judiciously using pesticides and chemical fertilizers
• Encourage reuse of water
• By preventing discharges from nuclear power plant
• By prohibiting direct washing of clothes and animals in water bodies used for drinking water supply
• Reducing oil spills
• Increasing vegetation cover to reduce soil erosion
• Public awareness

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